Self-Standing Riser and Buoyancy Device Deployment and Positioning System

ABSTRACT

A water-borne vessel for deploying a self-standing riser system is provided, wherein the vessel hull is configured to receive, transfer and deploy components of a self-standing riser system. The vessel hull includes at least a landing platform, a component transfer means, and a deployment platform suitable for deploying the riser components into associated surrounding waters. Various means of assisting the process whereby self-standing riser components are loaded onto the vessel and stored; transferred from receiving to deployment platforms; and deployed from the vessel into surrounding waters are also considered.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Non-ProvisionalApplication No. 12/274,814 filed Nov. 20, 2008, still pending, whichclaims the benefit of prior U.S. Provisional Application No. 61/003,748,filed Nov. 20, 2007.

FIELD OF THE INVENTION

The present invention relates generally to self-standing riser systemsused during energy exploration and production, and in a particularthough non-limiting embodiment, to a system useful for deployingself-standing risers and associated buoyancy devices in a variety ofoperating conditions.

BACKGROUND OF THE INVENTION

Over the past decade, there has been an increasing worldwide demand foroil and gas production. At present, however, oil and gas supplycontinues to lag far behind demand, a situation which has at timescontributed significantly to worldwide economic difficulties and couldwell present a major concern for many years to come.

In an effort to balance supply and demand, companies and governmentalentities have begun to explore and develop relatively marginal fields inthe deeper offshore waters of the Gulf of Mexico, West Africa andBrazil. However, due to high construction costs and limitedmanufacturing facilities, only a small number of mobile offshoredrilling units (MODUs) are being manufactured each year, therebyresulting in escalating “per day” unit costs and a shortage ofassociated offshore drilling, completion and workover equipment.

Moreover, even though the cost differential between drilling operationsand completion or workover operations is relatively modest (since MODUsusually perform all of these functions during a typical operation), mostsuch projects are still inefficient, because a MODU actively performingone function (e.g., drilling) is generally not able to accomplish anyother functions (e.g., completion or workover).

In other applications by this inventor, it has been shown that aself-standing riser system can be safely and reliably installed incommunication with a well head or production tree. Such risers by designare self-supporting, and provide all of the necessary risers, casing,buoyancy chambers, etc., required for exploration and production and ofoil, gas and other hydrocarbons. Self-standing risers also provide therequisite safety features required to ensure that the producedhydrocarbons do not escape from the system out into surrounding waters.For example, self-standing riser systems fully support bothsurface-based and semi-submersible platform interfaces, blow-outpreventers, production trees, and other common exploration andproduction installations.

Known self-standing riser systems require either a number of differentsurface vessels or a MODU for installation, due to the size and weightof riser stacks, drilling pipe, buoyancy devices, etc. For manyinstallations, expensive hull and deck modifications also have to bemade. Accordingly, few improvements in associated per-day costs havebeen realized.

There is, therefore, a need for a more cost-effective method ofinstalling self-standing riser systems, which does not require the useof MODUs.

SUMMARY OF THE INVENTION

A water-borne vessel for deploying a self-standing riser system isprovided, wherein the vessel hull is configured to receive, transfer anddeploy components of a self-standing riser system. The vessel hullincludes at least a landing platform, a component transfer means, and adeployment platform suitable for deploying the riser components intoassociated surrounding waters. Various means of assisting the processwhereby self-standing riser components are loaded onto the vessel andstored; transferred from receiving to deployment platforms; and deployedfrom the vessel into surrounding waters are also considered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a self-standing riser deployment vessel,according to example embodiments.

FIG. 1B is a schematic diagram depicting the submersion of aself-standing riser system, according to example embodiments.

FIG. 1C is a schematic diagram of a deployment vessel positioning acompleted self-standing riser system, according to example embodiments.

FIG. 1D is a schematic diagram of a deployment vessel releasing from acompleted self-standing riser system, according to example embodiments

FIG. 2A is a side view of a self-standing riser system deploymentvessel, according to example embodiments.

FIG. 2B is top view of a self-standing riser system vessel equipped witha buoyancy device loading bay, according to example embodiments.

FIG. 2C is a schematic diagram depicting a buoyancy device being loweredinto a buoyancy device loading bay, according to example embodiments.

FIG. 2D is a schematic diagram of a deployment vessel beginning itsrelease of a deployed buoyancy device stack, according to exampleembodiments.

FIG. 2E is a schematic of a deployment vessel having released its load,and leaving the site prior to commencement of drilling operations.

DETAILED DESCRIPTION

The description that follows includes exemplary systems, methods, andtechniques that embody various aspects of the presently inventivesubject matter. However, it will be readily understood by those of skillin the pertinent arts that the described embodiments may be practicedwithout one or more of these specific details. In other instances,well-known manufacturing equipment, protocols, structures and techniqueshave not been shown in detail in order to avoid obfuscation in thedescription.

Referring now to FIG. 1A, an example embodiment of a self-standing riserdeployment vessel 6 is depicted, comprising a plurality of buoyancydevices 2 temporarily attached to the bottom of the hull. In exemplaryembodiments, deployment vessel 6 is a workboat, anchor handling boat, orany other available vessel of suitable size and configuration; thelengths of such vessels might range, for example, from around 150 ft. toaround 300 ft., though these size estimates should not be deemed aslimitative.

Other embodiments of deployment vessel 6 comprise enough deck andstorage space to carry associated riser tubing 4, and additionalbuoyancy devices 2. Still further embodiments employ dynamic positioningequipment (e.g., a spar), which facilitate efficient and reliable riserstack deployment and installation on the sea floor.

In one embodiment, an entire string of risers is assembled with one ormore buoyancy devices interspersed as needed in order to providesufficient buoyancy for the entire system. The string is then deployedas a continuous structure and lowered to the sea floor in a controlledmanner. The top of the string is then secured and lifted so that it canbe moved over the drilling site and attached to the well. In otherembodiments, the system is deployed in a piecemeal fashion, withsections of a desired length being individually deployed andmechanically joined as the assembly is completed.

In the example embodiment illustrated in FIG. 1A, deployment vessel 6further comprises a hoisting frame 3 disposed near a moon pool 5. Thehoisting frame permits riser 4 stored within the vessel to be loaded andlowered or held in position. In various embodiments, the lowering,raising and holding of riser 4 is facilitated using conveyor belts,chains, rollers, etc. In one example embodiment, riser 4 is transferredfrom a storage container towards the moon pool 5 using a conveyor belt,and subsequently connected to a fastening device affixed to hoistingframe 3. The riser can then be deployed or held in a desired position ina safe and reliable manner.

Consistent with the example deployment vessel 6 illustrated in FIG. 1A,further embodiments also comprise loading mechanisms (e.g., frames,rails, etc.) used to load, guide and control the buoyancy devices 2.FIG. 1A, for example, depicts two buoyancy devices 2 disposed inmechanical communication with the bottom of the hull of the deploymentvessel 6. The buoyancy devices 2 are affixed to a carrying frame 1configured to reliably accommodate large, heavy loads. Carrying framerequirements will vary by project, but each such device should, atminimum, be capable of supporting the weight of one or more buoyancydevices. Electric, hydraulic or pneumatic lifts can be used to raise andlower the buoyancy devices, and ropes, chains, and tension lines reeledout from strategically placed winches can assist in the fine controlnecessary to ensure safe and controlled deployment of the buoyancydevices.

In some embodiments, each of said buoyancy devices 2 further comprises aconnector 14 (i.e., a flange or receptive housing, etc.) that allows forattachment of additional buoyancy devices 2 or riser assemblies 4.

In the example embodiment depicted in FIG. 1B, each of the buoyancydevices further admit to the passing of riser 4 through a void space inthe buoyancy devices by means of a hoisting frame 3, so that the riser 4can subsequently be attached to a subsurface wellhead 8 installed atop awell bore 9. A flanged member 18 can be used to help capture descendingriser and assist in connection of the riser to the wellhead.

In the example embodiment illustrated in FIG. 1C, deployment vessel 6 isused to lower a fully assembled self-standing riser system into positionfor attachment with wellhead 8. Guide frame 1 assists in the controlleddeployment of the riser near the surface, and a flanged member 14assists in capture of the lowered riser. In other embodiments,deployment vessel 6 utilizes dynamic positioning equipment (oralternatively, light equipment such as ropes, chains, winch lines, etc.)to lower, raise and support the riser stack as it is position above thewellhead. Further embodiments utilize buoyancy devices to tension thestack as deployment is carried out, and to dynamically position theriser between the vessel and the well.

As seen in FIG. 1D, once the self-standing riser system is deployed andattached to the well, the surface vessel releases its hold and thevessel can be used for other operations on a cost-effective basis. Insome embodiments, the vessel deploys the self-standing riser and leavesthe site so that other vessels (e.g., vessels with testing packages,separators, or even MODUs when one becomes available) can interface withthe system and initiate completion, testing or workover operations.

Referring now to FIG. 2A, a side view of a deployment vessel isillustrated, comprising a plurality of buoyancy devices 2 and a reliablemeans for deployment thereof. Some embodiments comprise one or more of aloading crane, a hoisting frame, buoyancy device transmission andpositioning means 5, etc., disposed near a moon pool.

As seen in FIG. 2B, it may be convenient that the moon pool is formed atthe aft end of the vessel. In an especially novel approach, the aft endis open, and the moon pool has only three sides 6, so that greaterflexibility in position is achieved. In still further embodiments, thebuoyancy devices 2 are loaded onto the deployment vessel from aneighboring service vessel, whereafter operations are carried out asdescribed above.

In the example embodiment depicted in FIG. 2A, a plurality of buoyancydevices 2 are loaded onto the deployment vessel from a neighboringvessel, positioned for deployment from the deployment vessel by atransmission means 5, and then deployed into a body of water in a safeand controlled fashion that ensures efficient operations and maintenanceof the buoyancy devices' structural integrity.

In some embodiments, a neighboring crane is used to lower the buoyancydevices onto a deployment vessel landing platform, as depicted in FIG.2A. The landing platform can be either flooded (in the event the devicesare intended for immediate deployment), or dry (in the deployment isintended for a later time, or if access is needed so as to permitoutfitting or maintenance). If the landing platform is dry, intake portsare provided so that it can later be flooded, allowing easiertransportation and deployment of the devices at or near the drillingsite (see, for example, FIG. 2C). Such embodiments would likely utilizewinches, fastening mechanisms, etc., to secure and facilitate safe andreliable control of the devices. The deployment vessel can thentransport and deploy the devices as described above.

In the example embodiment depicted in FIG. 2C, a barge or othertransport vessel is used to transfer additional buoyancy devices to thelanding platform of a deployment vessel by means of a rope, chain, winchline, etc. In one particular embodiment, the buoyancy devices are movedvia roller tracks toward an overhead gantry, hoisted by a crane or otherhoisting device, and lowered into the deployment pool.

In the example embodiment depicted in FIG. 2D, the buoyancy devices havebeen landed from a service vessel and lowered into the water. Thedevices are then towed in by a second deployment vessel and attached toits hull via winches, hooks, fastening mechanisms, etc., disposed inmechanical communication with the second deployment vessel. In FIG. 2E,the second deployment vessel has captured and secured the devices, andthe service vessel has released its line. The service vessel can thenrepeat the process until the desired number of buoyancy devices has beentransferred to a desired number of deployment vessels.

The foregoing specification is provided for illustrative purposes only,and is not intended to describe all possible aspects of the presentinvention. Moreover, while the invention has been shown and described indetail with respect to several exemplary embodiments, those of ordinaryskill in the art will appreciate that minor changes to the description,and various other modifications, omissions and additions may also bemade without departing from the spirit or scope thereof.

1. A water-borne vessel for deploying a self-standing riser system, saidvessel comprising: a vessel hull configured to receive, transfer anddeploy components of a self-standing riser system, wherein said vesselhull further comprises a landing platform, a transfer means, and adeployment platform.
 2. The water-borne vessel for deploying aself-standing riser system of claim 1, wherein said landing platformfurther comprises a hoisting means.
 3. The water-borne vessel fordeploying a self-standing riser system of claim 1, wherein said landingplatform further comprises an intake port for flooding said receivingplatform.
 4. The water-borne vessel for deploying a self-standing risersystem of claim 1, wherein said transfer means further comprises meansfor transferring self-standing riser components from said receivingplatform to said deployment platform.
 5. The water-borne vessel fordeploying a self-standing riser system of claim 4, wherein saidtransferring means further comprises a securing means for securing saidcomponents during transfer from said receiving platform to saiddeploying platform.
 6. The water-borne vessel for deploying aself-standing riser system of claim 1, wherein said deployment platformfurther comprises a receiving means for receiving self-standing risercomponents transferred from said receiving platform.
 7. The water-bornevessel for deploying a self-standing riser system of claim 1, whereinsaid deployment platform further comprises a securing means for securingself-standing riser components received from said transferring means. 8.The water-borne vessel for deploying a self-standing riser system ofclaim 1, wherein said deployment platform further comprises a hoistingmeans for hoisting self-standing riser components received from saidtransferring means into a deployment position.
 9. The water-borne vesselfor deploying a self-standing riser system of claim 1, wherein saiddeployment platform further comprises a deployment means for deployingself-standing riser components from said deployment platform intoassociated surrounding waters.
 10. The water-borne vessel for deployinga self-standing riser system of claim 1, wherein said water-borne vesselfurther comprises a storage area for storing self-standing risercomponents placed upon said vessel.